Stabilization of Formate Dehydrogenase in a Metal-Organic Framework for Bioelectrocatalytic Reduction of CO2

The efficient fixation of excess CO2 from the atmosphere to yield value-added chemicals remains crucial in response to the increasing levels of carbon emission. Coupling enzymatic reactions with electrochemical regeneration of cofactors is a promising technique for fixing CO2, while producing biomass which can be further transformed into biofuels. Herein, a bioelectrocatalytic system was established by depositing crystallites of a mesoporous metal-organic framework (MOF), termed NU-1006, containing formate dehydrogenase, on a fluorine-doped tin oxide glass electrode modified with Cp*Rh(2,2 '-bipyridyl-5,5 '-dicarboxylic acid)Cl-2 complex. This system converts CO2 into formic acid at a rate of 79 +/- 3.4mmh(-1) with electrochemical regeneration of the nicotinamide adenine dinucleotide cofactor. The MOF-enzyme composite exhibited significantly higher catalyst stability when subjected to non-native conditions compared to the free enzyme, doubling the formic acid yield.